1. Field of the Invention
This invention relates to herbicidal compositions, preparation thereof and processes of controlling unwanted plants using the herbicidal compositions.
2. Description of the Prior Art
All of the active substances which have hitherto been used as herbicides are the chemically synthetic compounds, which may sometime give rise to problems of environmental pollution. From a viewpoint of increasingly severe legal regulations of environmental pollution, the demand now increases to provide those herbicidal substances which can be rapidly decomposed in the surrounding conditions and cause no environmental contamination.
We described and claimed the antibiotic, SF-1293 substance and a microbiological process for the production thereof (see Japanese Pat. No. 827,768, U.S. Pat. No. 3,832,394 and German Pat. No. 2,236,599). It is now found that the SF-1293 substance as a herbicide can meet the requirements mentioned above since it is susceptible to metabolism and breakdown into harmless substances in the course of the material-circulation occurring in nature.
The SF-1293 substance (in the free acid form) is the compound of the formula: ##STR1##
As described in the aforesaid U.S. and German Patents, the SF-1293 substance is highly active to various fungal diseases of plants, including Pellicularia sasakii (sheath blight on rice) and Piricularia oryzae (rice blast).